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<h1 class="title">Display.qml 示例文件</h1>
<span class="subtitle">demos/calqlatr/content/Display.qml</span>
<!-- $$$demos/calqlatr/content/Display.qml-description -->
<div class="descr"> <a name="details"></a>
<pre class="qml">

  <span class="comment">/****************************************************************************
  **
  ** Copyright (C) 2017 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
  ** Software or, alternatively, in accordance with the terms contained in
  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see https://www.qt.io/terms-conditions. For further
  ** information use the contact form at https://www.qt.io/contact-us.
  **
  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
  ** as follows:
  **
  ** &quot;Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
  **   * Redistributions in binary form must reproduce the above copyright
  **     notice, this list of conditions and the following disclaimer in
  **     the documentation and/or other materials provided with the
  **     distribution.
  **   * Neither the name of The Qt Company Ltd nor the names of its
  **     contributors may be used to endorse or promote products derived
  **     from this software without specific prior written permission.
  **
  **
  ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ** &quot;AS IS&quot; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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  ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.&quot;
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  ** $QT_END_LICENSE$
  **
  ****************************************************************************/</span>

  import QtQuick 2.0
  import QtQuick.Window 2.0

  <span class="type"><a href="qml-qtquick-item.html">Item</a></span> {
      <span class="name">id</span>: <span class="name">display</span>
      property <span class="type"><a href="../qtqml/qml-real.html">real</a></span> <span class="name">fontSize</span>: <span class="name">Math</span>.<span class="name">floor</span>(<span class="name">Screen</span>.<span class="name">pixelDensity</span> <span class="operator">*</span> <span class="number">5.0</span>)
      property <span class="type"><a href="../qtqml/qml-bool.html">bool</a></span> <span class="name">enteringDigits</span>: <span class="number">false</span>
      property <span class="type"><a href="../qtqml/qml-int.html">int</a></span> <span class="name">maxDigits</span>: (<span class="name">width</span> <span class="operator">/</span> <span class="name">fontSize</span>) <span class="operator">+</span> <span class="number">1</span>
      property <span class="type"><a href="../qtqml/qml-string.html">string</a></span> <span class="name">displayedOperand</span>
      property <span class="type"><a href="../qtqml/qml-string.html">string</a></span> <span class="name">errorString</span>: <span class="name">qsTr</span>(<span class="string">&quot;ERROR&quot;</span>)
      property <span class="type"><a href="../qtqml/qml-bool.html">bool</a></span> <span class="name">isError</span>: <span class="name">displayedOperand</span> <span class="operator">===</span> <span class="name">errorString</span>

      <span class="keyword">function</span> <span class="name">displayOperator</span>(<span class="name">operator</span>)
      {
          <span class="name">listView</span>.<span class="name">model</span>.<span class="name">append</span>({ &quot;operator&quot;: <span class="name">operator</span>, &quot;operand&quot;: <span class="string">&quot;&quot;</span> })
          <span class="name">enteringDigits</span> <span class="operator">=</span> <span class="number">true</span>
          <span class="name">listView</span>.<span class="name">positionViewAtEnd</span>()
      }

      <span class="keyword">function</span> <span class="name">newLine</span>(<span class="name">operator</span>, operand)
      {
          <span class="name">displayedOperand</span> <span class="operator">=</span> <span class="name">displayNumber</span>(<span class="name">operand</span>)
          <span class="name">listView</span>.<span class="name">model</span>.<span class="name">append</span>({ &quot;operator&quot;: <span class="name">operator</span>, &quot;operand&quot;: <span class="name">displayedOperand</span> })
          <span class="name">enteringDigits</span> <span class="operator">=</span> <span class="number">false</span>
          <span class="name">listView</span>.<span class="name">positionViewAtEnd</span>()
      }

      <span class="keyword">function</span> <span class="name">appendDigit</span>(<span class="name">digit</span>)
      {
          <span class="keyword">if</span> (!<span class="name">enteringDigits</span>)
              <span class="name">listView</span>.<span class="name">model</span>.<span class="name">append</span>({ &quot;operator&quot;: <span class="string">&quot;&quot;</span>, &quot;operand&quot;: <span class="string">&quot;&quot;</span> })
          var <span class="name">i</span> = <span class="name">listView</span>.<span class="name">model</span>.<span class="name">count</span> <span class="operator">-</span> <span class="number">1</span>;
          <span class="name">listView</span>.<span class="name">model</span>.<span class="name">get</span>(<span class="name">i</span>).<span class="name">operand</span> <span class="operator">=</span> <span class="name">listView</span>.<span class="name">model</span>.<span class="name">get</span>(<span class="name">i</span>).<span class="name">operand</span> <span class="operator">+</span> <span class="name">digit</span>;
          <span class="name">enteringDigits</span> <span class="operator">=</span> <span class="number">true</span>
          <span class="name">listView</span>.<span class="name">positionViewAtEnd</span>()
      }

      <span class="keyword">function</span> <span class="name">setDigit</span>(<span class="name">digit</span>)
      {
          var <span class="name">i</span> = <span class="name">listView</span>.<span class="name">model</span>.<span class="name">count</span> <span class="operator">-</span> <span class="number">1</span>;
          <span class="name">listView</span>.<span class="name">model</span>.<span class="name">get</span>(<span class="name">i</span>).<span class="name">operand</span> <span class="operator">=</span> <span class="name">digit</span>;
          <span class="name">listView</span>.<span class="name">positionViewAtEnd</span>()
      }

      <span class="keyword">function</span> <span class="name">clear</span>()
      {
          <span class="name">displayedOperand</span> <span class="operator">=</span> <span class="string">&quot;&quot;</span>
          <span class="keyword">if</span> (<span class="name">enteringDigits</span>) {
              var <span class="name">i</span> = <span class="name">listView</span>.<span class="name">model</span>.<span class="name">count</span> <span class="operator">-</span> <span class="number">1</span>
              <span class="keyword">if</span> (<span class="name">i</span> <span class="operator">&gt;=</span> <span class="number">0</span>)
                  <span class="name">listView</span>.<span class="name">model</span>.<span class="name">remove</span>(<span class="name">i</span>)
              <span class="name">enteringDigits</span> <span class="operator">=</span> <span class="number">false</span>
          }
      }

      <span class="comment">// Returns a string representation of a number that fits in</span>
      <span class="comment">// display.maxDigits characters, trying to keep as much precision</span>
      <span class="comment">// as possible. If the number cannot be displayed, returns an</span>
      <span class="comment">// error string.</span>
      <span class="keyword">function</span> <span class="name">displayNumber</span>(<span class="name">num</span>) {
          <span class="keyword">if</span> (typeof(<span class="name">num</span>) <span class="operator">!=</span> <span class="string">&quot;number&quot;</span>)
              <span class="keyword">return</span> <span class="name">errorString</span>;

          var <span class="name">intNum</span> = <span class="name">parseInt</span>(<span class="name">num</span>);
          var <span class="name">intLen</span> = <span class="name">intNum</span>.<span class="name">toString</span>().<span class="name">length</span>;

          <span class="comment">// Do not count the minus sign as a digit</span>
          var <span class="name">maxLen</span> = <span class="name">num</span> <span class="operator">&lt;</span> <span class="number">0</span> ? <span class="name">maxDigits</span> <span class="operator">+</span> <span class="number">1</span> : <span class="name">maxDigits</span>;

          <span class="keyword">if</span> (<span class="name">num</span>.<span class="name">toString</span>().<span class="name">length</span> <span class="operator">&lt;=</span> <span class="name">maxLen</span>) {
              <span class="keyword">if</span> (<span class="name">isFinite</span>(<span class="name">num</span>))
                  <span class="keyword">return</span> <span class="name">num</span>.<span class="name">toString</span>();
              <span class="keyword">return</span> <span class="name">errorString</span>;
          }

          <span class="comment">// Integer part of the number is too long - try</span>
          <span class="comment">// an exponential notation</span>
          <span class="keyword">if</span> (<span class="name">intNum</span> <span class="operator">==</span> <span class="name">num</span> <span class="operator">||</span> <span class="name">intLen</span> <span class="operator">&gt;</span> <span class="name">maxLen</span> <span class="operator">-</span> <span class="number">3</span>) {
              var <span class="name">expVal</span> = <span class="name">num</span>.<span class="name">toExponential</span>(<span class="name">maxDigits</span> <span class="operator">-</span> <span class="number">6</span>).<span class="name">toString</span>();
              <span class="keyword">if</span> (<span class="name">expVal</span>.<span class="name">length</span> <span class="operator">&lt;=</span> <span class="name">maxLen</span>)
                  <span class="keyword">return</span> <span class="name">expVal</span>;
          }

          <span class="comment">// Try a float presentation with fixed number of digits</span>
          var <span class="name">floatStr</span> = <span class="name">parseFloat</span>(<span class="name">num</span>).<span class="name">toFixed</span>(<span class="name">maxDigits</span> <span class="operator">-</span> <span class="name">intLen</span> <span class="operator">-</span> <span class="number">1</span>).<span class="name">toString</span>();
          <span class="keyword">if</span> (<span class="name">floatStr</span>.<span class="name">length</span> <span class="operator">&lt;=</span> <span class="name">maxLen</span>)
              <span class="keyword">return</span> <span class="name">floatStr</span>;

          <span class="keyword">return</span> <span class="name">errorString</span>;
      }

      <span class="type"><a href="qml-qtquick-item.html">Item</a></span> {
          <span class="name">id</span>: <span class="name">theItem</span>
          <span class="name">width</span>: <span class="name">parent</span>.<span class="name">width</span> <span class="operator">+</span> <span class="number">32</span>
          <span class="name">height</span>: <span class="name">parent</span>.<span class="name">height</span>

          <span class="type"><a href="qml-qtquick-rectangle.html">Rectangle</a></span> {
              <span class="name">id</span>: <span class="name">rect</span>
              <span class="name">x</span>: <span class="number">16</span>
              <span class="name">color</span>: <span class="string">&quot;white&quot;</span>
              <span class="name">height</span>: <span class="name">parent</span>.<span class="name">height</span>
              <span class="name">width</span>: <span class="name">display</span>.<span class="name">width</span> <span class="operator">-</span> <span class="number">16</span>
          }
          <span class="type"><a href="qml-qtquick-image.html">Image</a></span> {
              <span class="name">anchors</span>.right: <span class="name">rect</span>.<span class="name">left</span>
              <span class="name">source</span>: <span class="string">&quot;images/paper-edge-left.png&quot;</span>
              <span class="name">height</span>: <span class="name">parent</span>.<span class="name">height</span>
              <span class="name">fillMode</span>: <span class="name">Image</span>.<span class="name">TileVertically</span>
          }
          <span class="type"><a href="qml-qtquick-image.html">Image</a></span> {
              <span class="name">anchors</span>.left: <span class="name">rect</span>.<span class="name">right</span>
              <span class="name">source</span>: <span class="string">&quot;images/paper-edge-right.png&quot;</span>
              <span class="name">height</span>: <span class="name">parent</span>.<span class="name">height</span>
              <span class="name">fillMode</span>: <span class="name">Image</span>.<span class="name">TileVertically</span>
          }

          <span class="type"><a href="qml-qtquick-image.html">Image</a></span> {
              <span class="name">id</span>: <span class="name">grip</span>
              <span class="name">source</span>: <span class="string">&quot;images/paper-grip.png&quot;</span>
              <span class="name">anchors</span>.horizontalCenter: <span class="name">parent</span>.<span class="name">horizontalCenter</span>
              <span class="name">anchors</span>.bottom: <span class="name">parent</span>.<span class="name">bottom</span>
              <span class="name">anchors</span>.bottomMargin: <span class="number">20</span>
          }

          <span class="type"><a href="qml-qtquick-listview.html">ListView</a></span> {
              <span class="name">id</span>: <span class="name">listView</span>
              <span class="name">x</span>: <span class="number">16</span>; <span class="name">y</span>: <span class="number">30</span>
              <span class="name">width</span>: <span class="name">display</span>.<span class="name">width</span>
              <span class="name">height</span>: <span class="name">display</span>.<span class="name">height</span> <span class="operator">-</span> <span class="number">50</span> <span class="operator">-</span> <span class="name">y</span>
              <span class="name">delegate</span>: <span class="name">Item</span> {
                  <span class="name">height</span>: <span class="name">display</span>.<span class="name">fontSize</span> <span class="operator">*</span> <span class="number">1.1</span>
                  <span class="name">width</span>: <span class="name">parent</span>.<span class="name">width</span>
                  <span class="type"><a href="qml-qtquick-text.html">Text</a></span> {
                      <span class="name">id</span>: <span class="name">operator</span>
                      <span class="name">x</span>: <span class="number">6</span>
                      <span class="name">font</span>.pixelSize: <span class="name">display</span>.<span class="name">fontSize</span>
                      <span class="name">color</span>: <span class="string">&quot;#6da43d&quot;</span>
                      <span class="name">text</span>: <span class="name">model</span>.<span class="name">operator</span>
                  }
                  <span class="type"><a href="qml-qtquick-text.html">Text</a></span> {
                      <span class="name">id</span>: <span class="name">operand</span>
                      <span class="name">font</span>.pixelSize: <span class="name">display</span>.<span class="name">fontSize</span>
                      <span class="name">anchors</span>.right: <span class="name">parent</span>.<span class="name">right</span>
                      <span class="name">anchors</span>.rightMargin: <span class="number">22</span>
                      <span class="name">text</span>: <span class="name">model</span>.<span class="name">operand</span>
                  }
              }
              <span class="name">model</span>: <span class="name">ListModel</span> { }
          }

      }

  }

</pre>
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   their respective owners.<br>    The documentation provided herein is licensed under the terms of the    <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation    License version 1.3</a> as published by the Free Software Foundation.<br>    Qt and respective logos are trademarks of The Qt Company Ltd.     in Finland and/or other countries worldwide. All other trademarks are property
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